Techniques for reducing the sub smoke flow in cigarette smoking are known as per U.S. Pat. No. 4,231,377 and Japanese Patent Disclosure (Kokai) No. 57-163,479. A technique for reducing the main and sub smoke flows in cigarette smoking is known as per Japanese Patent Disclosure (Kokai) No. 48-61, 699.
In U.S. Pat. No. 4,231,377, a magnesium compound such as magnesia or magnesium hydroxide is added to rolling material to reduce the sub smoke flow. This patent does not provide any description of the main smoke flow.
In Japanese Patent Disclosure (Kokai) No. 57-163,479, the sub smoke flow is reduced using a rolling material having a small amount of air permeation (about 0.5 to 8 coresta). However, this technique has its disadvantages of increase in the main smoke flow and the number of puffs.
Japanese Patent Disclosure (Kokai) No. 48-61,699 discloses wrapping shredded tobacco with two rolling materials. The first rolling material directly wraps the shredded tobacco and is added with up to 70%, based on the first rolling material, of activated carbon having a particle size of 0.177 mm or less and containing particles having a size of 0.44 mm or less in an amount of 25 to 50%. The second rolling material consists of general cigarette paper and covers the first rolling material. These two rolling materials reduce the main and sub smoke flows. However, according to this method, the thickness of the rolling material is increased and interferes with the rolling operation of a conventional cigarette making machine. This leads to a need for a modified cigarette making machine or the development of a new type of cigarette making machine. Even if rolling with a conventional cigarette making machine can be performed, activated carbon may be separated or peeled off during rolling, thus adversely affecting the rolling conditions. This also renders maintenance of the cigarette making machine difficult.